Dovetailed Step Stool

After I finish a large commission, I like to surprise my client during the holidays with a gift—this sturdy kitchen stepping stool. Making one is a pleasure because it's held together by nothing but dovetails, and I love hand cutting dovetails. A kitchen stool that will face hard use has to be strong. When you stand on the stool and hold onto its tall back for balance, you put extra strain on the joints. That's why this stool is dovetailed throughout, because dovetails make the strongest connection between wide boards. If they fit tight the mechanical interlocking alone is enough to hold boards at a rigid right angle. Adding glue is icing on the cake.

You'll need about six board feet of lumber (about $25), to make this stool. The one in these photos is made of cherry, but any wood will do, including pine. You'll also need some tempered hardboard, 1⁄4 in. and 1⁄2 in. plywood for the jigs and a router and router table. After you've made the jigs and tried them out, set aside one weekend to make the stool.You'll find three different kinds of dovetail joints in this stool: a tapered sliding dovetail that goes across the grain, through dovetails and straight-sliding dovetails that go with the grain.

Prepare the Wood
Flat wood is essential for successful dovetailing. Boards that are cupped across the grain will be nothing but trouble. Mill rough lumber to 7⁄8 in., taking an even amount off both sides. Sticker the boards so air circulates all around. After a few days, see if the boards are still flat. Joint again if you have to, and take the wood down to the final thickness of 3⁄4 in. Mill the wood for the back, seat and front from one wide board if you can. The cathedral arch figure will then flow nicely from one piece to another, especially if you center the arches down the middle of the board. Set aside some extra wood for setting up dovetailing operations. Make sure all your wood is exactly the same thickness.

Make the Template
A good template for the back is worth the effort. (Fig. A) You could lay out the pattern directly onto your 3⁄4-in. wood, but smoothing and sanding it will take more time than preparing a thin template. And having a template will allow you to make multiples. Make the template from 1⁄4-in. tempered hardboard, a material that's tough but easy to shape. A router bearing won't dent it. Cut the hardboard with a jigsaw or bandsaw. Smooth the roughly cut curves with a half-round file. Use a block plane to straighten the sides.

Run your hand around the template feeling for any hills or valleys. A smooth template will pay off in a back that needs only a light sanding.This template is the middle layer of a wonderful router jig that puts the bit right where you want it (Fig. B). Cut the top and bottom layers undersize and leave them rough. Screw the three layers together. Drill holes through the sandwich for screws that will hold it to the back. When you drill the finger hold and rout the dovetail socket you'll remove the pilot holes made by these screws.

Shape the Back and Front
Rip the solid wood for the back, seat and front to the same width. Crosscut the back board a bit longer than its final length. Align the template with the bottom end of the back and trace around it. Saw out the back, staying at least 1⁄16-in. away from the pencil line. Fasten the template sandwich to the face side of the back board. Clamp the whole assembly down to the bench. Rout around the back in a counterclockwise direction (Photo 1). You'll have to re-position the back to avoid bumping into the clamps, but make sure you rout each curve in one continuous pass. Rout the front board's arch in the same manner. You won't be able to screw the sandwich to the board, so use clamps instead.

Tapered Sliding Dovetail
The seat is joined to the back with a long sliding dovetail. Both the pin and socket are tapered. This joint is easier to fit and glue up than one that isn't tapered. The pin slides easily into the front of the socket. The last inch is the only tough part—you'll have to push hard to get the joint home. You'll be amazed with the strength of this joint!  A tapered dovetail sounds difficult to make, but it's really quite easy. The secret is to create all the tapers with one shim that's about 1⁄32-in. thick. Make the tapered socket with a foolproof jig (Figs. C) & (Figs. D). Use a standard 1⁄4-in. shank dovetail bit with a 14-degree pitch and 1⁄2-in. width. Clamp the jig down and rout away (Photo 2).

Make the long pin that slides into the socket on the router table (Photo 3). Adjust your router so it cuts a 5⁄16-in. pin, exactly the same length as the socket is deep. The easiest way to do this is to unplug the router, lay the stool's back on the router table and raise the bit until it touches the bottom of the socket. Tape shims onto both faces of a test piece to create the same taper as the socket. Try sliding the test piece into the socket. It should start easy and gradually tighten up. You should be able to pound it home with your fist. Adjust the fence to change the fit. When it's right, rout the real seat. Once the socket is cut you'll know exactly how long the front board must be. Slide the seat in place and measure from the bottom of the back to the top of the seat. Cut the front board to length.

Through Dovetails
The strongest through dovetails are fairly large in section. The width of a full pin should be about the same as its thickness, in this case, 3⁄4 in. The half-pins at either end of the joint should actually be a bit more than half the size of a full pin. Here they're 1⁄2-in. wide. The tails should be clearly larger than the pins for the joint to look right, but the exact proportion isn't important. I cut my dovetails by hand (see “Four Tips for Dovetailing by Hand,”). I can make them any size to fit the situation. You can use your favorite router jig to make through dovetails, but if it's a jig with fixed spacing you might have to alter the width of the stool a bit to make the pins and tails work out. In that case, be sure to lay out the spacing before you mill your lumber. Glue the front to the seat. Check for square. Plane or sand the dovetails flush. It's easier to hold two pieces in your vise now than the whole stool later.

Non-Tapered
Sliding Dovetails
A stretcher just above the arches locks in the front and back, making a rigid structure. This sliding dovetail isn't tapered because a taper isn't really necessary over this short distance. Make another socket jig to guide the router (Fig. E). Again, you'll need to size it to fit your router. Cut both sockets (Photo 4). Assemble the stool without glue before cutting the stretcher to length (Photo 5). Shape the dovetailed end of the stretcher on the router table. Test the fence setting with a scrap. The stretcher is pretty narrow and it's not safe to merely stand it up on end on the router table. Clamp a backer board alongside the stretcher so you have a wider bearing surface.

Assemble the Stool
Glue the seat to the back first, then turn the stool upside down and drop in the stretcher. (Fig. F) You won't need any clamps. After the glue is dry, plane all the sides flush. Trim the side rails to exact length and glue them on. Sand them even with the seat. Apply your favorite finish. Hitch up the sleigh and deliver a great holiday gift!

Source
MLCS, www.mlcswoodworking.com, (800) 533-9298, 1/2-in. 14-degree dovetail bit, #5405, $7.

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